MS Outlook 2007

I have a user that is using MS Outlook 2007, and every every so often when he hits reply or forward on an email with attachments it gives an error that "Operation Failed". That's all it says. It is a new HP Elitebook 8440p with Windows 7 32-bit. Can anyone tell my what would cause this? Thanks!

You might want to see how large the file is that they're forwarding. If using Outlook, are they connecting through an Exchange Server? If so, some servers are set to have a limit to how large files can be sent out. POP3 accounts have that sometimes too.

Is this forwarding to an outside account, can you send internally (if in a business?)